Reception of angular velocity modulated waves



37 2- H. TONlC ZK 2,282,104

RECEPTION 0F ANGULAR VELOCITY MODULA'IED WAVES Original Filed Dec. 22, 1939 5 sheets sheet l A INVENTOR HARRY/ZN/CK BY AZTTORNEY May 5, 1942. HQTUNICK RECEPTION OF ANGULAR VELOCITY MODULAIED WA V ES Original Filed Dec. 22, 1939 s Sheets-Sheet 2 INVENTOR I HARRY BY ATTORNEY RWQ GREY Am Que MESQQB "S 3S3 v mk Patented May 5, 1942 RECEPTION OF AN GULAR VELOCITY MODULATED WAVES Harry Tunick, Rye, N. Y., assignor to Radio Corporation of America, a corporation of Delaware Application October 16, 1940, Serial No. 361,413, which in turn is a division of application Serial No. 310,495, December 22, 1939. Divided and this application November 29, 1941, Serial No.

3 Claims.

This is a division of my application Serial No. 361,413, filed October 16, 1940, in turn a division of my copending application Serial No. 310,495, filed December 22, 1939. Figures 1 to '7 inclusive herein correspond, respectively, to original Figures 11, 12, 13, 13a, 14, 20 and 21 of my parent application Serial No. 310,495 and, respectively, to Figures 2, 3-, 4, 5, 6, 12 and 13 of my application Serial No. 361,413.

The main object of my present invention is to provide improved circuits for detecting frequency modulated waves. Other objects, as well as advantages, of my invention will be apparent as the more detailed description thereof proceeds.

It is to be clearly understood that the apparatus described herein may be employed for the reception of any type of angular velocity modulated waves such as phase modulated waves. In this event, however, the modulation amplifying circuits following the detector should be modified so that, for example, if phase modulated waves are received, the amplifying circuits should be modified so as to have a characteristic such that amplification falls off with increase in modulation frequency.

Figures 1, 2, 3 and 5 are schematic diagrams of radio receivers for receiving, demodulating and translating angular velocity modulated waves, it being noted that the receivers have different discriminators each employing principles and features of my present invention. Figure 4 is a curve explanatory of adjustments made in the discriminator in, for example, Figure 3; and Figures 6 and 7 are schematic wiring diagrams of alternative forms of discriminator circuits employing features and principles of my present invention.

In the frequency modulation receiver of Figure 1, frequency modulated waves picked up on antenna l are amplified by radio frequency amplifier 3 and combined in first detector 5 with waves from the local generator 1. The beat or intermediate frequency energy resulting from this combination in first detector 5 is amplified in an intermediate frequency amplifier 9 and then fed through tuned circuits l3 in pushpull to the grids I5, I! of balanced detector tubes l9, 2|. Another portion of the intermediate frequency wave energy is fed through condenser 23 in push-push to the screen grids 25, 21, which are connected in parallel, of detector tubes l9, 2|. The resultant audio frequency or signal output is fed through transformer 29, amplified by signal or audio amplifier 3| and then translated into sound by earphones or loudspeaker 33.

In the frequency modulation radio receiver of Figure 2, intermediate frequency energy appearing in tuned circuit H is inductively fed into coil 35, thereby exciting the screen grids 31, 39 in phase opposition. The control grids l5, l1 are connected in parallel and are excited cophasally from tuned circuit II by connection thereto through condenser 23 which passes all of the frequencies of intermediate frequency energy, as does also the coupling between circuit H and coil 35. The audio frequency or signal output of tubes l9, 2| are combined in phase opposition in the primary of transformer 29 and then fed to amplifier 3|. The output of amplifier 3| is fed to translating device 33, here shown as earphones.

In the receiver of Figure 3, intermediate frequency energy from intermediate frequency circuit H is inductively injected into tuned circuits 4|, 43. If desired, the coupling between the coil Ha. of circuit I and the coils'4la and 43a of circuits and 43 may be eliminated, in which case energy may be transferred from circuit into circuits 4|, 43 by condensers 45, 41. Or, if desired, circuit may be both inductively and capacitively coupled to circuits 4| and 43.

As illustrated in Figure 4, circuit 4| is tuned to or beyond one extreme of the intermediate frequency band of frequencies and circuit 43 is tuned to or beyond the opposite extreme frequency of the intermediate band of frequency modulated waves appearing in circuit H. Detectors l9, 2| will produce in transformer 29 the original audio frequency waves or signaling waves transmitted. The latter, as before, may be amplified in the signal or audio amplifier 3| and translated by device 33.

As an additional feature, part of the intermediate frequency wave energy from circuit maybe inductively fed through coil 5| coupled to coil Ho and lead 53 in push-push to the parallelly connected grids |5, I! of push-pull connected rectifier tubes l9, 2|. Variable condenser 55 may be provided, as shown, for adjusting the phase of the energy fed in push-push to the grids I5, II.

In the receiver of Figure 5, circuits 4| and 43 are adjusted and coupled as described in connection with Figure 4. Also, if desired, the additional or alternative coupling through condensers and 41 may be provided. It is to be noted, however, in Figure 5 that circuits 4| and 43 are connected to the control grids I5, ll rather than to the screen grids of tubes [9, 2|,

As so far described, the receiver of Figure 5 will operate to produce signals in the push-pull connected plate circuit of tubes I 9 and 2I which may be fed through transformer 29 to amplifiier 3| for translation in device 33. If desired, the suppressor grids GI, 63 may be connected in parallel to one side of circuit II, as shown, through large. I

Icy-passing condensers 65, 61. In this way, the

suppressor grids 6|, 63 are excited cophasally have a characteristic such that the amplifier output falls off with increase in frequency. The preferred correction circuit for the receivers described herein when used to receive phase modu lated waves is described in Crosby Patent No. 2,060,611.

The receiver or detector circuit of Figure 6 is provided with an input circuit I I described hereinbefore. The detector tubes I 2|, I23 are provided with anodes I25, I21, suppressor grids I29, I3I, screen grids I33, I35, control grids I31, I39 and cathodes I4I, I43. The control grids I31, I39 are connected in phase opposition by coil I45 coupled to coil I41 of circuit II. Additional push-push excitation of control grids I31, I39 is provided by and through condenser I49.

Screen grids I33, I35 are connected in phase opposition by coil I 5| coupled to coil I41. The screen grids may be additionally excited in pushpush by condenser I53 if desired.

The suppressor grids I29, I 3| are connected in phase opposition by coils I55, I 51 also coupled to coil I41. Additional suppressor grid excitation in push-push may be provided by condenser I59 if desired. Grids I31, I33 and I29 are excited cophasally with successively higher voltages. They may, of course, be excited with the alternating voltage of the same amplitude or with successively decreasing voltages or with any related voltages, depending upon the closeness of coupling of coils I45, I5I and I55 with coil I41. Grids I39, I35 and I3I of detector tube I23 are similarly excited, it being noted that the inductive coupling makes the group of grids of tube I23 excited respectively out of phase with the corresponding group of grids of tube I2I. The resultant audio signal frequency energy, as before, is combined in transformer 95 and utilized as found desirable.

In the receiving or detecting system of Figure 7, the intermediate frequency circuit I I is inductively coupled to pairs of off-tuned circuits IBI, I63; I65, I61 and I69, "I. The off-tuning of these circuits is as described in connection with Figures 3 and 4. The pair of circuits I6I, I63 are connected to the grids I31, I39 of detector tubes I2I, I23. The pair of off-tuned circuit I65, I61

are connected to the screen grids I33, I35; and, the pair of off-tuned circuits I69, I1I are connected to the suppressor grids I29, I3I of detector tubes I2I, I23, the anodes I25, I21 of which are connected as shown to the primary of signal frequency output transformer 95.

By suitable adjustment of coupling between circuit II and circuits IBI, I65 and. I69, the grids I39, I33 and I29 of tube I2I are excited cophasally and may be excited in successively increasing amounts or the sam amount or at different values of alternating voltage derived from input circuit II. The grids of tube I23 are correspondingly excited. That is, the grids of tube I23 are similarly excited as to value and cophasally with respect to each other, but anti-phasally or in phase opposition with respect to the grids of the other detector I2 I.

In connection with Figures 6, although not so illustrated, coil I45 is preferably tuned to the mean frequency by means of a condenser in shunt therewith and also preferably coil I5I should be so tuned and coils I55 and I51 taken together should be so tuned.

Having thus described my invention, what 1 claim is:

1. In combination, a pair of electron discharge systems each having an anode, a cathode and a multiplicity of grids, a series of parallel tuned circuits tuned to one side of a desired operating frequency connected between electrodes of one of said systems, another series of parallel tuned circuits tuned to a frequency on the opposite side of said mean frequency connected to electrodes of the other of said systems, means for feeding frequency modulated waves to said parallel tuned circuits, and means for deriving from said electrodes of said systems demodulated frequency modulated waves.

2. In combination, a pair of electron discharge devices each having an anode and cathode and a plurality of control grids, a first frequency discriminating circuit connected to and between a pair of like control grids of said devices, a second frequency discriminating circuit connected to and between a second pair of like control grids of said devices, and a de-modulation output circuit connected to and between the anodes of said electron discharge devices.

3. In combination, a source of substantially constant amplitude frequency modulated waves, a pair of electron discharge systems each having an anode, a cathode and a plurality of grids, a first frequency to amplitude converting circuit arrangement connected between and to a pair of like gridsof said systems, a second frequency to amplitude converting circuit arrangement connected between and to a second pair of like grids of said electron discharge systems, said converting circuit arrangements being fed with waves from said source of frequency modulated waves, and a de-modulation frequency circuit connected to and between the anodes of said electron discharge systems.

HARRY TUNICK. 

